This invention relates to a device for checking the zero of a rifle.
Rifle sighting devices, particularly telescope sights, are susceptible to movement on account of being dropped or hit. A rifle which has been so damaged is said to have xe2x80x9clost its zero,xe2x80x9d meaning that the bullet impact point with respect to the reticle is not the same as it was before the damage was sustained. The damage is not always obvious, and in the past the only way to determine whether a rifle had lost its zero was by firing it. The zero of a rifle also generally varies between individuals, so another way a rifle can lose its zero is by being sighted in for another individual.
A rifle owner is thus, as a rule, not entirely certain whether a rifle as retained its zero unless they have recently fired it and it has not left their possession and control. The risk of lost zero is substantial in situations where the rifle has been out of the possession and control of the shooter. For hunters and competition shooters, the risk is greater whether the rifle has been shipped to location and handled by baggage handlers, for example. For police and military, the risk is greater where the rifle has been in the possession of an armorer for example, where it could have been dropped, or rezeroed to meet the needs of another individual.
Hunters often arrive at the hunt location at night for a hunt the next dawn, and do not have the opportunity to fire the rifle at an unimportant target to check its zero, or they simply do not wish to fire the rifle on account of possibly disturbing nearby game. Competition shooters are often not allowed by their rules to fire sighter shots prior to firing for record. Police and military marksman cannot rely on being able to go to a range to check the zero of their rifle between checking it out from the armorer or weapons custodian and arriving at a situation where they may be called upon to use it. If the rifle has lost its zero, the bullet from the rifle will not impact where the shooter believes it will, and the risk of a missed shot is high.
A device to permit the zero of a rifle to be quickly checked without firing the rifle would be very desirable.
It is an object of this invention to provide such a device.
In accordance with a first embodiment of the invention, there is provided an apparatus to which a scope can be mounted for checking the zero of a rifle. It comprises a mandrel, an arm, and a bracket. The mandrel closely fits the rifle chamber and has a longitudinal axis, a front end, and a back end. The arm is mounted to the back end of the mandrel and extends transversely outwardly from the longitudinal axis of the mandrel. A bracket is mounted to the arm for mounting a sighting device, for example, a telescopic sight, to sight along a path approximately parallel to the axis of the mandrel. Since many shooters already own a used telescopic sight, they can easily make use of the device as just described.
Although there are many different types of rifle cartridges, they are based on relatively few cases. For example, the 30-06 Springfield, 280 Remington, 270 Winchester, 25-06 Remington, 8 mm-06 and 35 Whelen all employ essentially the same 30-06 parent case with different neck diameters to accommodate different sized bullets. The same mandrel can be employed with all these different rifles. Other basic case designs widely used for many different calibers include the 7 mm Mauser and 7.62 mm NATO (0.308 Winchester) cartridges.
In another aspect, the invention provides a non-firing method to determine whether a rifle has retained its zero. The method comprises providing a rifle with a mounted rifle scope which has been sighted in for the rifle. A sight-in checker device as hereinabove described is provided, with a checker scope previously sighted in to coincide with the sight-in of the rifle scope mounted on the bracket when the checker device is mounted on the rifle in a predetermined position. The mandrel of the checker device is then positioned in the chamber of the rifle and the checker device is positioned in the predetermined position with respect to the rifle. The rifle is then positioned in a stable position with the rifle scope centered on a target and the checker scope is then viewed to whether it is also centered on the target. If it is not, the reticle of the rifle can be adjusted to the same impact point indicated by the checker device.
A method is thus provided for checking the sight-in of a rifle, and adjusting it if necessary, without firing a shot.